Polymers (resins) having cyclic structures on the main chain and elsewhere, because they exhibit durability, especially outstanding heat resistance, owing to the cyclic structures, have been attracting attention as promising materials in a variety of technical fields where such properties are in demand, including the fields of engineering plastics, optical materials and resists.
Conventional methods for obtaining such resins include processes which couple together monomers having a cyclic structure by polycondensation or addition polymerization, and processes in which monomers without a cyclic structure are cyclized during addition polymerization. Of these, because methods for obtaining polymers having cyclic structures by cyclization during addition polymerization provide novel production methods which differ significantly from techniques in which first monomers having a cyclic structure are prepared, then the monomers are polymerized, the use of such production methods shows promise in a variety of technical fields that employ polymers having cyclic structures. In both approaches, methods involving addition polymerization carry out the polymerization of monomers having unsaturated bonds such as double bonds. Because molecular weight modification is generally easy and various vinyl monomers can be copolymerized under mild conditions, it is easy to adjust the physical properties in accordance with the intended application and to impart various functions. Hence, these processes are being investigated as methods of synthesizing resins for such applications as optical materials and resists which require a high degree and broad range of functionality.
In the meantime, it is recognized that, unlike the monomers commonly used in addition polymerization, monomers which cyclize during polymerization are special monomers. Such monomers are exemplified by α-(unsaturated alkoxyalkyl)acrylates having two unsaturated groups on a single molecule—an acryloyl group and an unsaturated alkoxy group, such as an α-(allyloxymethyl)acrylate, which has an allyl ether group as the unsaturated alkoxy group. This special monomer has a structure in which —CH2—O—CH2—CH═CH2 is bonded to the 2-position carbon atom at the double bond of the acryloyl group. A cyclizing reaction between the acryloyl group and the allyl ether group arises during polymerization, resulting in the formation of a polymer having cyclic structures. Although α-(allyloxymethyl)acrylates and monomers having a similar structure, i.e., α-(unsaturated alkoxyalkyl)acrylates, can thus be regarded as useful monomers which undergo cyclopolymerization and are able to provide polymers having cyclic structures on the main chain and the like, because of their distinctive nature, very little has been published to date on the preparation and properties of such monomers.
In the circumstances, a method has been disclosed for reacting, for example, methyl α-(hydroxymethyl)acrylate with ethyl alcohol to form allyl ether compounds such as the corresponding methyl α-(ethoxymethyl)acrylate (see, for example, Patent Document 1). In this method, an allyl ether compound having a structure in which ethoxymethyl or the like is bonded at the 2-position carbon atom of the double bond on the acryloyl group is prepared. However, nothing is mentioned concerning the formation of α-(unsaturated alkoxyalkyl)acrylates.
With regard to, for example, methods of preparing conventional α-(unsaturated alkoxyalkyl)acrylates such as α-(allyloxymethyl)acrylates, methods of preparing α-position substituted acrylates by reacting a specific dialkyl-2,2′-[oxybis(methylene)]bisacrylate with an active hydrogen group-containing compound have been disclosed (see, for example, Patent Document 2). In this patent document, hydroxyl group-containing compounds are listed as examples of the active hydrogen group-containing compound. One example mentioned is ally alcohol. In addition, methods of preparing allyl ethers by reacting a specific acrylic acid ester with a hydroxyl group-containing compound have been disclosed (see, for example, Patent Document 3).
In addition, although monomers having an allyl ether structure are not themselves distinctive monomers which form polymers having cyclic structures, a method of preparing allyl ether ester monomers by way of an esterification reaction between a specific α-allyl-ω-hydroxy-polyoxyalkylene and a specific aliphatic monocarboxylic acid has been disclosed as a method for preparing monomers having an allyl ether structure (see, for example Patent Document 4). Methods for preparing α-(allyloxymethyl)acrylates by reacting a halomethyl acrylate with an allyl alcohol have also been described (see, for example, Non-Patent Document 1).
In addition, it has been disclosed that compounds obtained by inserting an allyloxymethyl group at the α-position on an acrylic acid ester undergo cyclopolymerization, giving rise to soluble polymers which have tetrahydrofuran rings on the main chain (see, for example, Non-Patent Documents 1 and 2).    Patent Document 1: Japanese Patent No. 3943180 (pages 1 and 3 of the specification)    Patent Document 2: Japanese Patent Application Laid-open No. 2005-239610 (pages 1 and 3)    Patent Document 3: Japanese Patent Application Laid-open No. H8-325200 (pages 2 and 8)    Patent Document 4: Japanese Patent No. 3610331 (pages 1, 2 and 15 of the specification)    Non-Patent Document 1: Robert D. Thompson, et al.: Macromolecules, vol. 25, p. 6455-6459 (American Chemical Society), 1992 (US)    Non-Patent Document 2: Michio Urushizaki, and four others: Macromolecules, vol. 32, p. 322-327 (1999)